Among the proteins present in blood, there are some which vary in, for example, their concentration in response to diseases, and thus can be used as indicators in the diagnosis of diseases. For example, glutamic oxalacetic transaminase (GOT) is an indicator of hepatitis, serum amylase is an indicator of pancreatitis, and the ratio of albumin to globulin is an indicator of nephrosis. These proteins in blood (blood proteins) are analyzed, for example, using cellulose acetate membrane electrophoresis methods, among others. Further, hemoglobin (Hb) which is a blood protein, includes hemoglobin A (HbA), hemoglobin F (HbF), hemoglobin S (HbS), and glycosylated hemoglobin (a glycosylated product of hemoglobin). Among these, hemoglobin S (HbS) is abnormal hemoglobin in which the 6th glutamic acid of the β chain is substituted with a valine. HbS is a marker in the diagnosis of sickle-cell anemia. Glycosylated hemoglobin is hemoglobin that is reacted with glucose in blood, and is used as an indicator in the diagnosis and treatment of diabetes. Glycosylated hemoglobins include hemoglobin A1a (HbA1a), hemoglobin A1b (HbA1b), hemoglobin A1c (HbA1c), and GHbLys, among others. Hemoglobin A1c is a glycosylated hemoglobin where the β-chain N-terminal valine is glycosylated. Hemoglobin A1c is an indicator that reflects previous glucose levels and is monitored as part of routine physical examinations. Because blood proteins are important indicators of various diseases, the development of apparatuses that are capable of providing rapid and accurate analysis of blood proteins are highly desired.
Examples of methods of measuring hemoglobin in blood include immunological methods, enzymatic methods, affinity chromatography methods, HPLC methods and capillary electrophoresis (CE) methods. Because immunological methods and enzymatic methods can be applied to autoanalysis apparatuses, they have the advantage of being able to handle large numbers of specimens. However, such immunological methods and enzymatic methods lack measurement accuracy. Further, regarding separation principles, affinity chromatography methods have relatively low specificity for the glycosylated valine of β-chain N-terminal, and the glycosylated lysine in a Hb molecule that is to be a component of a measured value. Therefore, the measurement accuracy for hemoglobin A1c by affinity chromatography methods is low. HPLC methods are widely used as methods of measuring hemoglobin (see, for example, JP 3429709 B). However, HPLC methods require large and expensive specialized apparatuses, and it is difficult to reduce the size and cost of these apparatuses. For applications with a number of samples, analysis apparatuses for hemoglobin would have to be reduced in size. However, as described above, it is difficult for HPLC methods to satisfy this requirement.